Present-day advances in telephony, while sometimes referred to as "integrated systems", are actually "integrated" only from the point of view of the telephone network and in the limited sense that digital and analog signals are switched by much common equipment; but from the user's point of view, there is little or no integration in that there is a telephone either for voice communication, or for a data call or connecting a computer in a particular way similar to ordinary modem connections. The ISDN system (Integrated Services Digital Network) of AT&T, for example, as described in AT&T Technical Journal, January-February, 1986, Vol. 65, Issue 1, in conjunction with the AT&T Mode 7506 ISDN telephone handset, selectively operates multiple phones, including with LCD display to show the number being dialed and/or the number calling the telephone (so-called ANI or automatic number identification) and, through an RS232 connector at the back of the phone, enables the plugging in of one or more modems to enable data transmission totally independent of the communication use of the telephone. No simultaneity of voice communication and data exchange to a single telephone number is possible, let alone with user transparency. On any given phone call, the operation either is just exactly like a phone having no computer or other data equipment whatsoever, or it is a computer operation exactly like a modem having no audio phone conversation use whatsoever. If the user does not possess a computer or a data terminal, then the user has no means whatsoever to do anything beyond a normal phone connection with this system. Thus, there is nothing "integrated" in these systems from the user's point of view.
Underlying the present invention, however, is a very different philosophy that achieves simultaneously both the function of conducting conversation and effecting digital transfer of information (such as computer-computer data exchange, FAX transmission, etc.). Currently, the mode of exchange (audio, computer data, FAX data, etc.) is usually implicit in the telephone number being dialed; some numbers are FAX numbers, for example, and some computer numbers. By means of the present invention, however, a number of these services are handled by a single telephone number; automatically and without confusion, and with providing entirely new services as well. Particularly interesting are those which combine audio conversation with data transmission simultaneously.
To initiate such a service smoothly and to achieve automatic coordination of extended telephone services sensible by both humans and machines, it is essential that the equipment at both ends of the line and the conversing users be informed of the fact that the telephones are equipped for specialized services that are to be provided. This is achieved, in accordance with the invention, by the use of a particular signal, called the SMARTPHONE.TM. RECOGNITION SIGNAL (SRS) which serves as the basis for much of this automatic recognition and mode selection. Briefly, an SRS is a particular in-band, complex, time-varying unique or distinctive audio signal, chosen with regard to a number of criteria later described. Once such an SRS has been transmitted, recognized, and responded to, all parties on the line (whether human user or machine) are aware that this is as SRS-equipped call. They are then ready to exchange further signals, if necessary, which can select a number of features and transmission modes as desired. The use of a later-discussed Digital Signal Processor (DSP), such as the Texas Instruments TMS320 series or Motorola DSP56000 series, as described in the Motorola technical data bulletin DSP56001, 1988 (pages 1-60), is a convenient means to make effective use of the flexibility made possible by the invention.